This invention relates to a power factor control system for operating an inverter-driven a-c induction motor at a constant desired power factor, to reduce power consumption, regardless of load variations on the motor.
Power factor control circuits have been developed for varying the power input to an induction motor as load conditions change in order to conserve energy and to improve the motor efficiency. In the absence of power factor control, the reactive volt amps (reactive power) of an induction motor can be relatively high when the motor is unloaded or only partially loaded, and this is very wasteful of electricity. The power factor control system of the present invention, which is especially useful when the induction motor is powered by the output a-c voltage from an inverter, is considerably simpler in construction than the prior power factor controls and exhibits a significant improvement in performance.